1. Field of Art
The disclosure relates generally to pumps, particularly reciprocating pumps, such as mud pumps used in the recovery of oil and gas. More particularly, the disclosure relates to piston components for creating and maintaining a seal between the piston and a surrounding pump cylinder.
2. Background of Related Art
Mud pumps are commonly used for conveying drilling mud during well drilling operations, such as for the recovery of oil and gas. Because of the need to pump the drilling mud through several thousand feet of drill pipe, such pumps typically operate at high pressures. Also, it is necessary for the drilling mud to emerge from the drill bit at a high flow rate in order to provide lubrication and cooling to the bit and to provide a vehicle for removal of drill cuttings from the earth formation being drilled. Further, the pressure generated by the mud pump contributes to the total downhole pressure, which is important and provided to prevent well blowouts.
Conventional mud pumps generally require interference between the sealing element of the piston and the surrounding cylinder to assure a seal between the two components and to provide sufficient material to maintain the seal while allowing for wear over the effective service life of the piston. This interference, however, results in a frictional load on the piston, which reduces pump efficiency. Moreover, the combined effect of the frictional forces resulting from the reciprocating contact between the piston seal and the cylinder, and the abrasive nature of drilling mud passing through the pump at high pressure is especially harmful to the sealing element. As the piston moves, edges of the sealing element experience wear and may become damaged. In some instances, the frictional force may be sufficient to cause the sealing element to detach from the piston.
Accordingly, means for maintaining a seal between a pump piston and a surrounding cylinder that also minimize wear to the piston components and frictional loads between the piston and cylinder are desirable.